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Just teach my kid the math

solipsys.co.uk

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Re: Just teach my kid the math

#31

Post by huffmsa »

mratzloff wrote: post #23

When calculating in my head or on paper, I value quick estimations moving to greater refinement. Common Core math seems somewhat similar to this. I never subtract, only add up from low to high. If the two numbers have the same number of differing digits, I move from most significant digit to least: 73-57=10+6. If they cross a round number threshold greater than 10s, I get to a convenient base first: 2018-1995=5+18; 1…

> 2018 - 1995 = 8 + 15.

Now I too start with the addition, but my brain very much thinks in the vertical stacking of the numbers, moving right to left. How do we get from 5 to 8? Add 3, how do we get from 9 to 1 when adding: plus 2. How do we get from 9 to 0: plus 1, which we already have from the 9 to 1 case, so we pass the 1 here to the left. 1 to 2, plus 1, again using the value passed to us.

Little surprise I prefer functional languages.

Re: Just teach my kid the math

#32

Post by meuk »

mratzloff wrote: post #23

When calculating in my head or on paper, I value quick estimations moving to greater refinement. Common Core math seems somewhat similar to this. I never subtract, only add up from low to high. If the two numbers have the same number of differing digits, I move from most significant digit to least: 73-57=10+6. If they cross a round number threshold greater than 10s, I get to a convenient base first: 2018-1995=5+18; 1…

Well, it is super useful do be able to do exact arithmetic. For example, to not get scammed when you buy anything, or share a bill. I've seen American university students who don't know how to compute a percentage of a given amount - so I'm not very impressed by common core math to be honest.

That being said, it's probably a cultural thing too. I noticed that in the USA (at least in California?) it is customary to exclude the taxes from the price that is displayed on the price tag. Since the tax rate is different for different products, it's pretty hard to compute the actual price that you pay, and in practice you just take whatever you need and don't have an idea what you pay. In addition, it is not very usual to split the bill (I'm not talking about simply dividing the price by the number of people, but about actually computing the price of the stuff you ate, and not paying more than that).

When I go to the grocery store, I usually keep a sum of the price in my head while I pick products. That way I'll know if something is off at the counter.

Re: Just teach my kid the math

#33

Post by thanatropism »

dazc wrote: post #4

The original source you linked to in the article is a lot easier to read. sorry/ https://medium.com/q-e-d/just-teach-my-kid-the-expletive-mat...

It has horrible always-there headers and footers that take a third of my 12" screen.

Web designers really need to get their act together. Nothing of such bad quality gets out of the door in any other real industry.

Re: Just teach my kid the math

#34

Post by rmah »

maximexx wrote: post #30
merraksh wrote: post #29

Earlier quoted context omitted.

I mean, what's the point of drilling stupid sums if you'll hardly ever need it in your life? "Hardly ever"? So when checking the restaurant bill, the change at the grocery shop, the tax return, a bank investment proposal, the costs of building/renovating a house, the time left for a mortgage, do you always use a calculator?

If I need to be sure? Yes!

Haha, I do not trust machines -- I check the calculator by doing the math by hand.

Re: Just teach my kid the math

#35

Post by Clubber »

mratzloff wrote: post #23

When calculating in my head or on paper, I value quick estimations moving to greater refinement. Common Core math seems somewhat similar to this. I never subtract, only add up from low to high. If the two numbers have the same number of differing digits, I move from most significant digit to least: 73-57=10+6. If they cross a round number threshold greater than 10s, I get to a convenient base first: 2018-1995=5+18; 1…

>From my understanding, the Common Core approach to math is much closer to this approach I developed intuitively than the traditional methods.

It is. I recently had to help my daughter with common core math and I saw the similarities.

I think the biggest problem people have with it is at first it's impossible to help your kids with homework which is frustrating for both the parent and the kid. I had to learn it before I could help her with it.

Now all we need to do is finally covert to the metric system.

Re: Just teach my kid the math

#36

Post by yorwba »

lsc wrote: post #14
ThomPete wrote: post #7

Earlier quoted context omitted.

Understanding why has always been my primary way to learn things. Do you have any suggestions for books or courses I could dig into to better understand this approach. My oldest who is 8 is quite good at math and on the math team and his school does do a lot to teach them but I want to help him how to think. In almost every other field I can but I am not good enough at math to understand which "games" to play.

I personally find Serge Lang's "Basic Mathematics" to be super useful in explaining the "why" of a particular formula in pre-college level math, as most books at my current level just seem to say "memorize this" He has an explanation of why x^0 is 1 and not 0 that doesn't involve calculus, for instance.

What would be an explanation that involves calculus? The only one I know is that x^(a+b) = x^a * x^b holds for positive a and b, and to uphold that pattern, it's necessary that x^0 = 1, x^-1 = 1/x and so on. For me, all of that was covered long before calculus.

Re: Just teach my kid the math

#37

Post by Fnoord »

meuk wrote: post #32
mratzloff wrote: post #23

When calculating in my head or on paper, I value quick estimations moving to greater refinement. Common Core math seems somewhat similar to this. I never subtract, only add up from low to high. If the two numbers have the same number of differing digits, I move from most significant digit to least: 73-57=10+6. If they cross a round number threshold greater than 10s, I get to a convenient base first: 2018-1995=5+18; 1…

Well, it is super useful do be able to do exact arithmetic. For example, to not get scammed when you buy anything, or share a bill. I've seen American university students who don't know how to compute a percentage of a given amount - so I'm not very impressed by common core math to be honest. That being said, it's probably a cultural thing too. I noticed that in the USA (at least in California?) it is customary to ex…

> When I go to the grocery store, I usually keep a sum of the price in my head while I pick products. That way I'll know if something is off at the counter.

I wouldn't be able to CBA w/that during grocery shopping, I got way more to do whilst grocery shopping. Adhering my shopping list whilst checking for deals, and getting the correct items and correct amount. Figuring out in my head what combines with what recipe-wise.

For grocery shopping I ask for the receipt and then verify afterwards while discussing with my partner. Sometimes something's off in our advantage, sometimes in our disadvantage. Since its grocery shopping, we're talking about a few EUR here and there. If its non-grocery shopping, then I take quicker note.

As a rule of thumb the following rule appears to apply for me: the more expensive the item(s) the more cautious I am (denotes quality), but the more items the less cautious I am as well (denotes quantity). Why? Because its easier to do the former, and the latter becomes more difficult till we get to the CBA point.

Instead, I go for some deals, and then allow myself some treats as well, but never too much of either. The result is I mostly follow the grocery shopping list but I never know beforehand how much I exactly gotta pay, but I pay electronic either way; not with cash. I noticed when I've been in Germany and paid with cash, I took far better note of prices. Incidentally, groceries are generally cheaper in Germany as well...

Re: Just teach my kid the math

#38

Post by empath75 »

credit_guy wrote: post #16

My problem with the "new math" is the lack of volume. Developing a sense for the numbers is best done by working more with numbers; in the "old math" kids had to do thousands of additions in the first and second grade, and developed ten times the sense of numbers compared to kids today. Theory is theory, but practice is practice. Just get over the addition and multiplication, please. That's not where the true math is…

Learning by rote doesn’t teach you anything.

Re: Just teach my kid the math

#39

Post by michaelchisari »

jonsen wrote: post #8
ColinWright wrote: post #3

Earlier quoted context omitted.

My (very limited) experience of more recent homework is that it makes perfect sense in the context of what the teachers are trying to teach, but no sense out of context to people who learned their maths decades ago. If you'd care to send me a photo of an example of the homework then I can try to give you some context and understanding. My contact details can be derived from my HN profile. I might be a little slow to…

... makes perfect sense in the context of what the teachers are trying to teach ... What's the point with home work then? School takes the best part of a childs day, and when they don't make it through, the parents can finish with a tired child.

I don't mind this new way of teaching math, but on this note, I liked what Sal Khan had to say about flipping the process for school and homework.

He proposed that students should watch lectures at home with a few problems for familiarity, and that classroom time should be spent working through problems in a guided environment. This allows students to pause, rewind, rewatch, etc. the lectures and move at their own pace, while getting expert guidance on the problems in person (and not relying on parents who may not have even looked at the source material in decades).

Re: Just teach my kid the math

#40

Post by yorwba »

empath75 wrote: post #38
credit_guy wrote: post #16

My problem with the "new math" is the lack of volume. Developing a sense for the numbers is best done by working more with numbers; in the "old math" kids had to do thousands of additions in the first and second grade, and developed ten times the sense of numbers compared to kids today. Theory is theory, but practice is practice. Just get over the addition and multiplication, please. That's not where the true math is…

Learning by rote doesn’t teach you anything.

Spending lots of time on the treadmill won't make you a great soccer player, but still trains a basic skill useful for the game. Similarly, doing lots of arithmetic by hand isn't enough to solve all kinds of real-world problems, but it does help develop an intuition for numbers, which then helps with the problem-solving part.
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